In addition to the conditions which we have just considered, hospital zones must fulfil two obligations, which we shall examine in turn.

(a) ' Exclusion of military transport '. -- The Monaco Draft expressly authorized military convoys in transit to make temporary use of lines of communication and transport crossing a hospital zone. Certain experts had, however, opposed the provision, pointing out that the halting of a convoy in a zone might give rise to abuses and disputes as to the duration of the halt and the strategical purpose served by it, quite apart from interfering with the proper functioning of the zone. Taking these important arguments into consideration, the International Committee of the Red Cross felt bound to exclude such utilization of the zone entirely when drawing up the Draft Agreement. [p.633] The same experts had also put forward objections to the passage of convoys of civilians in transit, but later conferences did not reexamine this problem and the text of Article 5, as it stands, does not appear to exclude such transit. The practice is not to be recommended, however, in view of the difficulties to which it may give rise. A zone may possess an aerodrome, provided it only serves zonal needs. The obligation laid down in this Article will undoubtedly influence the siting of any zones set up. Preference will be given to areas in which there are no main railway lines or roads, for fear of paralysing the system of communications, and interfering with the normal life of the country.

(b) ' Absence of military defence '. -- Since the zones must be respected and protected by the Parties to the conflict they quite obviously may not be defended by military means. Should enemy forces penetrate to the boundaries of a zone, no resistance will be offered, and the enemy will have the right to assume control of the zone, but not to modify its organization. In the same way, batteries of anti-aircraft guns may not be sited in the zone. On the other hand, the use of the term "military means" implies that zones may be defended against other dangers. They will, for example, possess a police force capable of maintaining law and order; this police force may prevent individuals from penetrating unlawfully into the zone, either individually or in groups. Again, it is legitimate for a civil defence service to exist in the zone and for air raid shelters to be constructed there. There is no mention, either in the Draft Agreement or in the Convention, of the flight of aircraft over zones. In the absence of any special provision, it must be assumed that both friendly and enemy aircraft may fly over them.